The present invention concerns maltitol crystals of particular forms and crystalline compositions containing them. It also relates to a particular process for obtaining these crystals and compositions.
For a very long time, maltitol was presented only in the form of low content syrups.
Then, maltitol was marketed in the form of amorphous and impure powders.
To the knowledge of the Applicant company, it was only about 1980 that prominence was given to maltitol crystals. Previously, this polyol was not known as forming crystals easily.
The only crystalline form known up till now for maltitol is the anhydrous form, which is subject to wide-ranging patent protection on behalf of the HAYASHIBARA company (U.S. Pat. No. 4,408,041).
The so-called xe2x80x9cmassxc3xa9xe2x80x9d techniques on the one hand and those of water crystallisation on the other, are today almost the only processes in industrial use. The products thus obtained are of very variable crystallinity and are not all particularly well suited to certain applications such as chewing-gum or chocolate.
On the other hand, there are other applications where these products are not totally satisfactory. This is the case for example when it is required to use maltitol to replace saccharose and lactose in pharmaceutical dry forms such as capsules, medicines of the soluble powder type, tablets and food preparations in powdered form to be dissolved. This is also the case when it is required to effect the same kind of substitution in sweetened foods such as powdered drinks, desserts, cake preparations or chocolate-flavoured or vanilla-flavoured breakfast powders.
It is noted for these particular applications, particularly for pseudo-crystalline maltitol powders obtained by the xe2x80x9cmassxc3xa9xe2x80x9d technique and to a lesser degree for crystalline maltitol powders obtained by crystallisation in water, that these have one or more defects in particular for example those of not flowing easily, of being liable to cake or to knot together, of dissolving only very slowly in water, of being bad vehicles for compression or of not meeting the criteria for identification and purity set by different pharmacopoeias.
In its wish to improve on the prior art, the Applicant company has sought to perfect maltitol compositions which do not have the flow, caking, dissolving or compression defects presented by known maltitol powders. Admittedly, it might have been thought possible to meet the identified need with other polyols. But, this is demonstrably not so since none of them has characteristics of solubility, hygroscopicity, sweetened flavour and fusion as close to saccharose as maltitol.
And it is while working to perfect these compositions that the Applicant company was able to isolate, in a surprising and unexpected way, two particular forms of maltitol crystals, one bipyramidal and the other prismatic.
It is to the credit of the Applicant company that it has succeeded, after conducting extensive research, in explaining the existence of these two forms of maltitol crystals. It has indeed demonstrated that, against all expectation, the form of the maltitol crystals was a function of the maltotriitol content of a maltitol syrup intended for crystallisation. The Applicant company has noted that by controlling the maltotriitol content of a maltitol syrup, it was possible to direct the form of the maltitol crystals towards one or other of the forms or towards a mix of the two forms, when this maltitol syrup is subjected to a crystallisation stage.
As a result, according to a first aspect, the invention relates to modified maltitol crystals, characterised in that they are bipyramidal in form including two regular tetrahedrons juxtaposed by their square section base with sides of about 50 to 500 xcexcm, thus constituting regular octahedrons with edge length of about 50 to 500 xcexcm.
According to a second aspect, the invention also concerns modified maltitol crystals, characterised in that they are prismatic in form ending with plane faces constituting a tetrahedron, and in that they are 100 to 400 xcexcm long and about 20 to 100 xcexcm wide.
The forms of crystallisation (bipyramidal or prismatic) inevitably have significant repercussions both for manufacture and for applications. Thus, a semi-crystallised maltitol mass, including a certain percentage of prismatic crystals is more viscous than a mass including the same percentage of bipyramidal crystals, all things being equal in other respects, and this particularly when the crystals are of significant size.
Therefore to prepare atomised maltitol, it is preferable to accept suspensions which are very low in maltotriitol and additionally including bipyramidal rather than prismatic crystals so as to avoid caking. In other respects, the use of bipyramidal maltitol crystals proves advantageous in the production of chocolate (more thickened mass before refining), of chewing-gums (possibility of retaining a flexible texture with a large amount of powdered maltitol), of pharmaceutical dry forms (greater consistency of flow) etc.
On the other hand, a prismatic form is more compressible and enables low crystal content caking, as is sometimes required (chewing-gums, chewing-gum centres to be sugar coated).